From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754241AbcHXMRB (ORCPT ); Wed, 24 Aug 2016 08:17:01 -0400 Received: from mail-wm0-f67.google.com ([74.125.82.67]:35357 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752485AbcHXMQ7 (ORCPT ); Wed, 24 Aug 2016 08:16:59 -0400 Date: Wed, 24 Aug 2016 14:16:31 +0200 From: Michal Hocko To: Arnd Bergmann Cc: Vladimir Davydov , Johannes Weiner , Andrew Morton , Tejun Heo , Mel Gorman , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] mm: memcontrol: avoid unused function warning Message-ID: <20160824121630.GG31179@dhcp22.suse.cz> References: <20160824113733.2776701-1-arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160824113733.2776701-1-arnd@arndb.de> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 24-08-16 12:23:00, Arnd Bergmann wrote: > A bugfix in v4.8-rc2 introduced a harmless warning when CONFIG_MEMCG_SWAP > is disabled but CONFIG_MEMCG is enabled: > > mm/memcontrol.c:4085:27: error: 'mem_cgroup_id_get_online' defined but not used [-Werror=unused-function] > static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) > > This moves the function inside of the #ifdef block that hides the > calling function, to avoid the warning. > > Signed-off-by: Arnd Bergmann > Fixes: 1f47b61fb407 ("mm: memcontrol: fix swap counter leak on swapout from offline cgroup") > Acked-by: Michal Hocko > Acked-by: Vladimir Davydov Thanks a lot for respinning this Arnd! > --- > mm/memcontrol.c | 36 ++++++++++++++++++------------------ > 1 file changed, 18 insertions(+), 18 deletions(-) > > This is the alternative to the original patch, as suggested by Michal Hocko. > Andrew, please pick whichever version you like better. > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 2ff0289ad061..9a6a51a7c416 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4082,24 +4082,6 @@ static void mem_cgroup_id_get_many(struct mem_cgroup *memcg, unsigned int n) > atomic_add(n, &memcg->id.ref); > } > > -static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) > -{ > - while (!atomic_inc_not_zero(&memcg->id.ref)) { > - /* > - * The root cgroup cannot be destroyed, so it's refcount must > - * always be >= 1. > - */ > - if (WARN_ON_ONCE(memcg == root_mem_cgroup)) { > - VM_BUG_ON(1); > - break; > - } > - memcg = parent_mem_cgroup(memcg); > - if (!memcg) > - memcg = root_mem_cgroup; > - } > - return memcg; > -} > - > static void mem_cgroup_id_put_many(struct mem_cgroup *memcg, unsigned int n) > { > if (atomic_sub_and_test(n, &memcg->id.ref)) { > @@ -5821,6 +5803,24 @@ static int __init mem_cgroup_init(void) > subsys_initcall(mem_cgroup_init); > > #ifdef CONFIG_MEMCG_SWAP > +static struct mem_cgroup *mem_cgroup_id_get_online(struct mem_cgroup *memcg) > +{ > + while (!atomic_inc_not_zero(&memcg->id.ref)) { > + /* > + * The root cgroup cannot be destroyed, so it's refcount must > + * always be >= 1. > + */ > + if (WARN_ON_ONCE(memcg == root_mem_cgroup)) { > + VM_BUG_ON(1); > + break; > + } > + memcg = parent_mem_cgroup(memcg); > + if (!memcg) > + memcg = root_mem_cgroup; > + } > + return memcg; > +} > + > /** > * mem_cgroup_swapout - transfer a memsw charge to swap > * @page: page whose memsw charge to transfer > -- > 2.9.0 -- Michal Hocko SUSE Labs